In a Winchester-type disk drive, an actuator is rotatably mounted to the chassis of the disk drive which carries the read/write heads. The actuator is positioned in response to an address signal so that the heads become positioned along an addressed track of the magnetic disk.
When power is removed from the disk drive, it is desireable to move the actuator to a position which causes the heads to be removed from or positioned away from active data storing tracks on the disk. This removal of the heads being widely-known in the art as "parking" the heads. Once the heads are parked, it is desirable to latch the actuator in the parked position, thereby allowing the disk drive to be moved from one location to another or be able to withstand unintentional vibrations and shock.
To latch the actuator in the parked position, a solenoid may be provided for engaging the actuator. For example, in U.S. Pat. No. 4,807,072, a head positioner control mechanism with head-locking for magnetic disk drive is disclosed. The transducer head is locked by a locking lever which pivots in a plane parallel to the disk plane for movement in and out of locking engagement with a member jointly rotatable with the head arm. The solenoid holds the locking lever out of engagement with the rotary member during data transfer between the disk and head. Upon completion of data transfer or when power is removed from the disk drive, the solenoid becomes deenergized permitting the locking lever to be sprung into locking engagement with the jointly rotatable member of the head arm.
A disadvantage and limitation of the device disclosed in the above-mentioned patent is that during operation of the disk drive, an electrical current needs to be continuously applied to the locking solenoid to keep the locking lever retracted. This current generates heat in the solenoid windings which may cause failure of the solenoid. It is therefore highly desirable to provide a locking solenoid wherein the current could be removed from the solenoid, which would normally cause the locking lever to assume the locking position, yet maintain the locking lever retracted during active operation of the disk drive.